$\dfrac{4}{10} - \dfrac{8}{3} = {?}$
Explanation: $ = {\dfrac{4 \times 3}{10 \times 3}} - {\dfrac{8 \times 10}{3 \times 10}} $ $ = {\dfrac{12}{30}} - {\dfrac{80}{30}} $ $ = \dfrac{{12} - {80}}{30} $ $ = -\dfrac{68}{30}$